1. Field of the Invention
The present invention relates to an electrical drive-in tool for driving in fastening elements and including a driving ram displaceable in a guide, and a drive unit including a drive flywheel having a first component forming at least a circumferentially arranged rim, and a second component, and a motor for rotating the flywheel. The present invention also relates to a drive flywheel for an electrical drive-in tool.
2. Description of the Prior Art
In electrical drive-in tools of the type described above, the driving ram is accelerated by the flywheel that is driven by a motor. In drive-in tools, the drive-in energy, which is supplied by an accumulator, amounts maximum to about 35-40 j. In drive-in tools, which were developed on the basis of a flywheel principle, the energy which is stored in the flywheel, must be transferred to the driving shaft by a coupling.
A drive-in tool of the type described above is disclosed in U.S. Pat. No. 4,928,868. In the drive-in tool of U.S. Pat. No. 4,928,868, the driving ram is displaced between a motor-driven flywheel and an idler wheel. In order to frictionally couple the driving ram with the flywheel, the driving ram is displaced toward the flywheel by an adjusting mechanism, is pressed against the circumferential surface of the flywheel, and is accelerated. The flywheel is formed of two components. The first component forms the circumferentially arranged rim to which the driving ram is coupled. The rim is formed of steel in order to take into consideration high frictional forces. The second component includes a hub and is formed of a lighter material than steel.
A drawback of the drive-in tool according to U.S. Pat. No. 4,928,868 consists in that the increase of the drive-in energy can be achieved only by increase of the rotational speed of the flywheel or by increase of the flywheel size. The drawback of an increased rotational speed consists in that the coupling of the driving ram to the flywheel becomes more difficult, and slippage and resulting wear increases. If the volume of the flywheel increases, the entire drive-in tool becomes more bulky and is difficult to handle.
Accordingly, an object of the present invention is a drive-in tool of the type discussed above in which a high drive-in energy can be obtained in a technically simple way, and the above-mentioned drawbacks of the known drive-in tool are eliminated.